Optical scanning systems, such as those used for facsimile recording, commonly employ a periodic scanning mechanism, such as a galvanometer beam sweep device, through which a modulated beam of light (e.g. from an injection laser diode (ILD) source) is directed toward and swept across an object of interest, (e.g. a recording medium). During the recording operation, the beginning of a sweep interval must be accurately located in order to assure system synchronization and alignment of successive traces of the swept recording beam. This is usually accomplished through the use of a start (or end) of sweep photodetector and a dedicated deflection mirror disposed at a preselected end of sweep point of travel of the beam. As the beam is swept periodically across a field of view, it is intercepted by the dedicated deflection mirror at a prescribed point of its travel and the deflected beam is directed onto the photodetector, from which an end of (start of) sweep signal is coupled to the signal processing electronics. For exemplary illustrations of the use of such an end of sweep detection arrangement in an optical scanning system, attention may be directed to the U.S. Pat. Nos. to Hosterman et al 3,692,414, Fleischer 3,750,189, Erdman et al 3,809,891 and Sato 4,214,154.
Unfortunately, the types of mechanisms described in the above-referenced patent literature introduce or add complexity to the overall scanning and signal processing components as they require the use of additional hardware in the recording apparatus housing. In addition, the recording apparatus themselves are often cumbersome mechanical units and thereby do not lend themselves to present day needs of system compactness and simplicity.